178 lines
6.5 KiB
Markdown
178 lines
6.5 KiB
Markdown
Creates a new network. The `DRIVER` accepts `bridge` or `overlay` which are the
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built-in network drivers. If you have installed a third party or your own custom
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network driver you can specify that `DRIVER` here also. If you don't specify the
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`--driver` option, the command automatically creates a `bridge` network for you.
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When you install Docker Engine it creates a `bridge` network automatically. This
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network corresponds to the `docker0` bridge that Engine has traditionally relied
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on. When you launch a new container with `docker run` it automatically connects to
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this bridge network. You cannot remove this default bridge network but you can
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create new ones using the `network create` command.
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```bash
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$ docker network create -d bridge my-bridge-network
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```
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Bridge networks are isolated networks on a single Engine installation. If you
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want to create a network that spans multiple Docker hosts each running an
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Engine, you must create an `overlay` network. Unlike `bridge` networks overlay
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networks require some pre-existing conditions before you can create one. These
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conditions are:
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* Access to a key-value store. Engine supports Consul, Etcd, and Zookeeper (Distributed store) key-value stores.
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* A cluster of hosts with connectivity to the key-value store.
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* A properly configured Engine `daemon` on each host in the cluster.
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The `dockerd` options that support the `overlay` network are:
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* `--cluster-store`
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* `--cluster-store-opt`
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* `--cluster-advertise`
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To read more about these options and how to configure them, see ["*Get started
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with multi-host
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network*"](https://docs.docker.com/engine/userguide/networking/get-started-overlay/).
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It is also a good idea, though not required, that you install Docker Swarm on to
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manage the cluster that makes up your network. Swarm provides sophisticated
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discovery and server management that can assist your implementation.
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Once you have prepared the `overlay` network prerequisites you simply choose a
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Docker host in the cluster and issue the following to create the network:
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```bash
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$ docker network create -d overlay my-multihost-network
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```
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Network names must be unique. The Docker daemon attempts to identify naming
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conflicts but this is not guaranteed. It is the user's responsibility to avoid
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name conflicts.
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## Connect containers
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When you start a container use the `--network` flag to connect it to a network.
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This adds the `busybox` container to the `mynet` network.
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```bash
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$ docker run -itd --network=mynet busybox
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```
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If you want to add a container to a network after the container is already
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running use the `docker network connect` subcommand.
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You can connect multiple containers to the same network. Once connected, the
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containers can communicate using only another container's IP address or name.
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For `overlay` networks or custom plugins that support multi-host connectivity,
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containers connected to the same multi-host network but launched from different
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Engines can also communicate in this way.
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You can disconnect a container from a network using the `docker network
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disconnect` command.
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## Specifying advanced options
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When you create a network, Engine creates a non-overlapping subnetwork for the
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network by default. This subnetwork is not a subdivision of an existing network.
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It is purely for ip-addressing purposes. You can override this default and
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specify subnetwork values directly using the `--subnet` option. On a
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`bridge` network you can only create a single subnet:
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```bash
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$ docker network create -d bridge --subnet=192.168.0.0/16 br0
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```
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Additionally, you also specify the `--gateway` `--ip-range` and `--aux-address`
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options.
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```bash
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$ docker network create \
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--driver=bridge \
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--subnet=172.28.0.0/16 \
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--ip-range=172.28.5.0/24 \
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--gateway=172.28.5.254 \
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br0
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```
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If you omit the `--gateway` flag the Engine selects one for you from inside a
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preferred pool. For `overlay` networks and for network driver plugins that
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support it you can create multiple subnetworks.
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```bash
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$ docker network create -d overlay \
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--subnet=192.168.0.0/16 \
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--subnet=192.170.0.0/16 \
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--gateway=192.168.0.100 \
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--gateway=192.170.0.100 \
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--ip-range=192.168.1.0/24 \
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--aux-address="my-router=192.168.1.5" --aux-address="my-switch=192.168.1.6" \
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--aux-address="my-printer=192.170.1.5" --aux-address="my-nas=192.170.1.6" \
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my-multihost-network
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```
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Be sure that your subnetworks do not overlap. If they do, the network create
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fails and Engine returns an error.
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### Network internal mode
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By default, when you connect a container to an `overlay` network, Docker also
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connects a bridge network to it to provide external connectivity. If you want
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to create an externally isolated `overlay` network, you can specify the
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`--internal` option.
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### Network ingress mode
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You can create the network which will be used to provide the routing-mesh in the
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swarm cluster. You do so by specifying `--ingress` when creating the network. Only
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one ingress network can be created at the time. The network can be removed only
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if no services depend on it. Any option available when creating an overlay network
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is also available when creating the ingress network, besides the `--attachable` option.
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```bash
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$ docker network create -d overlay \
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--subnet=10.11.0.0/16 \
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--ingress \
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--opt com.docker.network.mtu=9216 \
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--opt encrypted=true \
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my-ingress-network
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```
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### Run services on predefined networks
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You can create services on the predefined docker networks `bridge` and `host`.
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```bash
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$ docker service create --name my-service \
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--network host \
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--replicas 2 \
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busybox top
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```
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### Swarm networks with local scope drivers
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You can create a swarm network with local scope network drivers. You do so
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by promoting the network scope to `swarm` during the creation of the network.
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You will then be able to use this network when creating services.
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```bash
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$ docker network create -d bridge \
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--scope swarm \
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--attachable \
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swarm-network
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```
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For network drivers which provide connectivity across hosts (ex. macvlan), if
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node specific configurations are needed in order to plumb the network on each
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host, you will supply that configuration via a configuration only network.
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When you create the swarm scoped network, you will then specify the name of the
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network which contains the configuration.
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```bash
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node1$ docker network create --config-only --subnet 192.168.100.0/24 --gateway 192.168.100.115 mv-config
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node2$ docker network create --config-only --subnet 192.168.200.0/24 --gateway 192.168.200.202 mv-config
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node1$ docker network create -d macvlan --scope swarm --config-from mv-config --attachable swarm-network
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```
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